Multiple studies have shown a direct correlation between exposure to sunlight and cataract formation. The solar-induced cataract,or brunescent cataract, is characterized by increased browning of the lens, which progressively removes a greater portionof the visible spectrum from reaching the retina. While this is the major cause of blindness in the world today, the mechanisms involved are poorly understood. The protein-bound chromophores present in aged human lenses are capable of absorbing UVA light (320-400 nm) and causing extensive protein damage due to the generation of reactive oxygen species (ROS). The work here proposes to quantitatively determine the ability of these isolated proteins to generate ROS and to document the increase in the formation of each of these ROS, and to document the increase in the formationof each of these ROS during aging and brunescent cataract formation. Since UVA irradiationcasues the oxidation of Trp and His residues and protein corsslinking, these properties will be determined in brunescent lenses to confirm the extend of UVA damage already extant inthese lenses. Further, the ability of specific scavengers and quenchers willbe employed in vitro to determine their ability to penetrate into the protein aggregates isolated from the lenses, as they may be effective as preventative agents inthe formation of solar cataracts.